[TowerTalk] Chrome Molly tube.

[Dubovsky, George]

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Jim Lux
Sent: Tuesday, November 23, 2004 9:22 AM
To: Tower (K8RI); TOWERTALK at contesting.com
Subject: Re: [TowerTalk] Chrome Molly tube.


----- Original Message -----
From: "Tower (K8RI)" <tower at rogerhalstead.com>
To: <TOWERTALK at contesting.com>
Sent: Monday, November 22, 2004 8:58 PM
Subject: [TowerTalk] Chrome Molly tube.


> I'm looking for some chrome molly tube to replace the structural steel
I'm
> using now.
>
> I currently have 2 22-23 foot long pieces of 1 1/2 inch with 1/4 inch
wall
> butt welded together.  Over the splice is a 24 foot length of 2" which
just
> nicely fits over the  1 1/2.
>
> When the winds hit 50 to 70 MPH the thing looks like a blue gill fly
rod
> that just tied into a Bass. I find it amazing the VHF and UHF antennas
have
> held together for two winters.
>
> My thoughts are the Chrome molly tube would be more rigid, albeit a
whale
of
> a lot more expensive.

Why do you want it more rigid/stiff?  Just because it flexes doesn't
mean
it's going to fail (that's more a function of the material yield point).
A
stiffer mast will change the distribution of loads which might have
unforeseen side effects.

Jim
W6RMK

One reason might be, that while a stiffer mast might change the
distribution of loads, they will likely be known (or knowable). A
springy mast, as it deflects and recovers in variable winds, applies
significant and difficult-to-calculate loads to various parts of the
antenna/tower structure. Aluminum antenna parts, in particular, can
reach their fatigue limit at an accelerated rate when exposed to this
sort of "exercise".

geo - n4ua

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